Explosion-proof refrigerator



Oct. 10, 1961 A. E. MANNING ETAI. 3,003,683

EXPLOSION-PROOF mmm'roa 2 Sheets-Sheet 1 Filed Aug. 1, 1958 Leonard 1770:! BY 7 Arron/viz) INVE TQRJ: m: z 1; J3,

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EXPLOSION-PROOF REFRIGERATOR Filed Aug. 1/1958 2 Sheets-Sheet 2 T1115. L l

, I S I J INVENTORY.

Alerf ljflannin Zeomna'l Kai/e35 BY M "ArrokrvEY United States Patent 3 003 683 EXPLOSION-P1160! REFRIGERATO Albert E. Nutley, and K140121112! I. Matless,

- Cedar ve, asslgnors to e ore Inc pontlon of New Jeisey a cor- Filed Aug. 1, .1958, Ser. No. 752,605

3 Claims. (Cl. 230-17) This invention relates in general to explosion-proof eleetrrcal apparatus, and particularly refrigerators, especrally refrigerators for industrial use comprising an electrically operated motor-compressor and electrical controls such as relays, thermostats and overload protectors.

A primaryobject of the invention is to provide apparatus of this character and particularly industrial refigerators whichshall embody novel and improved features of construction to permit operation of the apparatus in locations in which flammable gases or vapor are, or may be, present in the ambient air without danger of explosion as a result of sparking of the electrical equipment.

Another object of the invention is to provide in an explosion-proof refrigerator, a novel and improved construction and combination of an electrical motor and a refrigerant compressor driven thereby and hermetically sealed in one casing which has an integral steel housing unit orcontaine'r for electrical control apparatus for the motor and compressor, a cover for said housing unit or container to prevent escape of flame from within the container, outlet conduits for electric wires leading from said housing unit to a main control switch, and means for sealing said outlet conduits to prevent escape of flame therefrom into the ambient atmosphere. v

Other objects, advantages, and results of -the invention will be brought outbythe following description in conjunction with the accompanying drawings in which FIGURE 1 is a front'perspective view of one type of refrigerator embodying the invention portions of which are broken away for clearness in illustration;

FIGURE 2 is a top plan thereof; I

FIGURE 3 is an enlarged elevational view of the mo tor-compressor, condenser coil and electrical outlet'conduits taken approximately from the plane of the line 3-3 of FIGURE 2;

. FIGURE 4 is a further enlarged perspective view of the motor-compressor and a portion of the electrical conduit leading therefrom, with the major portion of the cover of the housingunit or container for certain parts of the electrical control apparatus broken away;

FIGURE 5 is an enlarged transverse vertical sectional view through one of the conduit sealing devices approximately on the plane of the line 5-5 of FIGURE 3;

FIGURE 6 is a fragmentary vertical longitudinal sectional view approximately on the plane of the line'6--6 of FIGURE 5; and

FIGURE 7 is a wiring diagram of the electrical apparatus. r v, I

For the purpose of illustrating the principles of the invention, it has been shown as embodied in one type of refrigerator, but it will be understood'by those skilled in the art that the invention is equally susceptible to use with other types of electrical refrigerators and apparatus.

As shown, the refrigerator includes the usual main casing or housing A having one or more refrigerating compartments normally closed by a hinged door B and above which is located an evaporator unit C of generally known construction which is connected in the usual way with a condenser coil D mounted on the back of the housing A The compressor is driven by an electrical motor in the usual way and has its outletH connected to the upper end of the condenser D which is in the form of a zig-zag coil of tubing 'and the other end of which is connected by a tube Kto the inlet of the evaporator C which is of known construction and only schematically illustrated and the outlet of which is connected by a tube L to the suction side or inlet of the compressor as indicated at M.

A capillary tube N connects the compressor in known manner to a sensing unit for control of the temperature,

- and the motor-compressor unit has an integral housing or container 0 for known electrical control apparatus generally designated P whichusually includes overload protectors, relays and thermostats. While the electrical apparatus per se forms no part of the invention, to facilitate understanding of the invention, a wiring diagram is shown in FIGURE 7 and includesthe motor-compressor terminals 1 and 2 that are connected to opposite terminals of a relay generally designated 3, the solenoid of which is connected to one terminal of a control unit 4 the other terminal of which is connected to one terminal of the line switch 5 whose other terminal is connected throughfan overload protector 6 to the third terminal 7 of the motor-compressor. The housing or container 0 has a section 8-that is preferably integral with the easing of the motor-compressor and which has a wide flange 9 to which is movably secured a cover 10 by bolts or cap screws 111, the abutting surfaces of the flange 9 and the cover being machined to such close tolerances and the cover being bolted so securely to the flange of the housing that heat or flame arising from combustion or explosion of flammable gases within the housing and escaping between the flange and the cover will be so restricted and cooled as. to eliminate the possibility of communicating such heat or flame to the surrounding exterior atmosphere, in such a manner as toignit'e flammable gases in the ambient atmosphere.

Wires '12 for connecting the control apapratus P in an electrical circuit with the linefextend through an outlet bushing 13 that is threaded into the wallet the housing and said wires are threaded through a conduit generally designated Q to an explosion-proof main switch R5, that is shown as mounted on a bracket S which is secured to the frame ,6 on which the condenser coil D is mounted.

In addition to the sealing of the control apparatus in the housing 0, the invention contemplates the explosionproof sealing of the wires 12in the conduit so that ignition of flammable gases or vapors in the vicinity of the refrigerator, such asmight occur from sparks in the conduit, will be prevented. For this purpose a sealing device T forms a portion of the'conduit Q and is interposed be tween and has a fluid-tightconnection with the outlet fitting l3 and an explosion-proof llexiblemetal pipe or hose U and ,another sealing device V explosion-proof fluid-tight connections with said flexible pipe U and the explosion-proof switch R.

More particularlytdescribing the. sealing devices, the device"'T includesmhollowmaincr bodyisection 14 having an opening 15 in one side thereof which is normally closed by. a screw plug 16 that has an opening 17 therethrough and through an extension 18 thereof for insertion of a semi-fluidorplastic sealing compound, the I opening 17 normally being closed by a plug 19 Tubular extensions 20 project integrally from opposite sides of the body 14 in alignment with each other so that the wires 12 may be threaded through the device and through a and connected to the compressor of a motor-compressor unit E that is mounted on a support F which may be set on the floor and is preferably connected to and carried by the rigid metal frame G on which the condenser D is mounted.

nipple 20', an elbow 21 and a union coupling 22 into the flexible coupling hose U, the joints between the nipple, elbow, coupling, and hose being fluid-tight or explosion-proof, with engagement of at least five full threads.

While the manner of sealing the wires in the device may be varied, preferably a thin walled bushing 23 is inserted into each of the extensions 20 and has an interior circumferential groove 24 into which suitable packing material, such as asbestos fibers, may be pressed through the opening 15 of the housing when the plug is removed from said opening and after the Wires have been threaded through the device. The plug 16 is then screwed into the body and a suitable plastic sealing compound 25 is inserted through the opening 17 into the hollow body as shown in FIGURE 5.

The sealing device V has a straight tubular body 26 and an upwardly inclined tubular branch 27 that is normally closed by a screw plug 28; and one end of the housing 26 is connected to the hose U by a union coupling 29 while the other end of the tubular body 26 is connected by a nipple to the casing of the explosionproof switch R. The wires passing from the sealing device T through the hose U also pass through the tubular body 26 and are connected to the terminals of the switch R; and these wires are sealed in the sealing device V in about the same manner in which they are sealed in the sealing device T, the sealing compound being inserted through the branch 27.

With this construction and combination of parts it will be seen that the apparatus may be located .and operated in locations in which flammable gases or vapors are present in the ambient air without danger of explosion as a result of flame or sparks that may be produced in the electrical parts. The invention provides novel explosionproof electrical controls and wiring that are simple and relatively inexpensive both in manufacture and installation. Any flames or sparks that might originate in the housing will be restricted and cooled so as to eliminate the possibility of passage of the heat or flame to the surrounding exterior atmosphere and will also be prevented by the sealing device T from entering the conduit Q. Also the sealing devices T and V seal off the hose U and couplings 22 and 29 from the apparatus housing 0 and from the main line switch R, and the sealing device V seals ofi the switch R from the hose U and the remainder of the conduit Q. a

While the construction of the refrigerator itself is relatively immaterial, it will be understood that generally the frame G will be channel shaped in cross section and have the condenser coil mounted thereon and the frame will be preferably attached to the exterior of the rear wall of the refrigerator housing A, as by bolts or screws passing through openings 31 in the frame into the rear "wall of the housing to provide a shaft for the passage of cooling air around the condenser coil as best shown in FIGURE .2.

It will also be understood that the evaporator C is mounted within the insulated-housing or shell A and that said housing or shell does not contain any wiring, lights, switches or any other devices which could produce a spark or flame.

While the now preferred embodiment of the invention has been illustrated and described, it will be understood that this is primarily for the purpose of illustrating the principles of the invention-and that modifications and changes may be made in the details of construction and the invention may :be embodied in other types of apparatus, all within the spirit and scope of the invention. For example, the number of the .sealing devices T and V may be varied to suit difierent conditions, some ap- 4 paratus requiring one such sealing device and other apparatus requiring two or more sealing devices.

What we claim is:

1. In an explosion-proof refrigerator, the combination with a motor-compressor unit, including an electric motor and a refrigerant compressor driven thereby hermetically sealed in one casing, of a housing integral with said casing and having therein electrical control apparatus for said unit, said housing having a flange and a cover removably secured thereto with a flameproof joint, an explosion-proof main switch, wires electrically connecting said control apparatus to said switch, and an explosion proof conduit for said wires having explosion-proof connections With said housing and with said switch and including between said housing and said switch at least one sealing device that includes a hollow body through which said wires are threaded and in which is a plastic sealing compound that seals the wires in said body and closes the conduit thereby preventing passage of flame and fluid in the conduit from either side of said body to the other.

2. In an explosion-proof refrigerator as defined in claim 1, said explosion-proof connections between said conduitand said housing and between said conduit and said switch are screw threaded with engagement of at least five full threads.

3. In an explosion-proof refrigerator, the combination with a motor-compressor unit including an electric motor and a refrigerant compressor driven thereby hermetically sealed in one casing, of a housing integral with said casing and having therein electrical control apparatus for said unit, said housing having a flange and a cover removably secured thereto with a flame-proof joint, an explosion-proof main switch, wires electrically connecting said control apparatus to said switch, and an explosionproof conduit for said wires, including a nipple screw threaded into said housing, a sealing device including a hollow body having a screw-threaded connection with said nipple, a second nipple screw threaded into said hollow body, a flexible explosion-proof coupling hose, means having screw-threaded connections with both said nipple and said hose for connecting them, a second sealing device including a hollow body having a screwthreaded connection with said hose, and means having screw-threaded connections with both said second sealing device and said switch for connecting them, said wires extending from said control apparatus to said switch through said conduit and the hollow 'body Of each said sealing devices having a sealing compound therein that seals said wires in said body and seals said conduit against passage of flame and fluid in the conduit from either side of the body to the other.

References Cited in the file of this patent UNITED STATES PATENTS 254,268 Brooks Feb. 28, 1882 2,368,492 Ralston Jan. 30, 1945 2,478,701 Maginniss Aug; 9, 1949 2,887,061 C-ametti et a1 May 19, 1959 2,900,436 Appleton Aug. 18, 1959 OTHER REFERENCES Publication; Bureau of Mines, Technical Paper 101, Permissible Explosion-Proof Electric Motors for Mines, 11 pages. 

